FREMANTLE drew a line in the sand and ended a six-year Western Derby drought on Sunday, standing up to win a thrilling clash against West Coast by 15 points and delivering a blow to their rival's finals hopes.

The Dockers kept their own season alive in front of a frenzied Optus Stadium crowd of 51,692 and ended an 11-game losing streak against the Eagles, winning 12.7 (79) to 9.10 (64) in a famous Derby.

DOCKERS v EAGLES Full match coverage and stats

Both WA clubs remain in contention for a finals spot, but will need to win in round 23 and hope other results fall their way, with the Eagles falling out of the top eight for the first time since round six and losing control of their destiny.

The Dockers had been challenged to draw a line in the sand by club greats Shaun McManus and Paul Hasleby, and the young team did that in veteran David Mundy's record-equalling 353rd game.

They built a game-high 40-point break early in the second quarter on the back of ferocious pressure and an attacking mindset with the ball, hanging on during an extended Eagles' fightback in the second half.

Glendinning-Allen medallist Caleb Serong (32 disposals, six clearances and two goals) was brilliant in a hard-nosed and skilful performance that inspired his team early and then dragged them over the line.

West Coast kicked 5.2 to 2.5 in the second half and will rue a wasteful second term in which it kicked 1.5. The Eagles dominated the third quarter with 24 inside 50s to give but added three goals to one.   

They booted back-to-back goals to open the final quarter and cut the margin to six points, but Serong delivered the breathing space his team needed with a magnificent snap from the pocket.  

Defender Luke Ryan was a brick wall with 26 disposals, 10 marks and 11 rebound 50s, while Mundy (28, seven clearances and a goal) continued a great season in his record-equalling game.  

STAR EAGLE SORE Gun midfielder's season in doubt

Adam Cerra (21, five clearances and a goal) was crucial in Andrew Brayshaw's absence, while Sean Darcy (27 hit-outs, seven clearances and a goal) held his own in an entertaining ruck battle with Nic Naitanui.

West Coast looked in good shape when Josh Kennedy booted two of the opening three goals, and its star-studded midfield had control of the centre bounce.

It was a burst that didn't last, however, as the Dockers took control of the game and played the best football of their season, piling on seven of the next eight goals.

The young Dockers grew in confidence and started to push around their more experienced opponents, tackling in packs when they didn't have the ball and repeatedly breaking the Eagles' tackles when they did.

They controlled possession and entered the first break with a 30-point lead, igniting a frenzied home crowd.

When Cerra and Lachie Schultz kicked back-to-back goals to open the second term, the margin was a game-high 40 points and the Eagles looked bereft of answers. 

They finally got the game on their terms for a period thereafter, controlling possession and taking the speed out of the game, but missed opportunities meant they didn't make up the ground they needed.

They kicked 1.5 for the quarter to Fremantle's 2.0, cutting the margin to 31 points and setting up a second-half scrap as the Eagles mounted a long fightback that ultimately fell short.

Dockers' opening ambush
Fremantle's thrilling opening ambush was built on ferocious workrate and tackling to force turnovers high up the ground, and an ability to switch into attack mode as soon as they won the ball and catch the Eagles out of position. They hit targets inside 50 better than they have all season and, in contrast to much of their campaign, kicked straight. Their 8.2 (50) was the highest first quarter of the season by any team, and the Dockers' best first quarter since round three, 2015, when they last won a Derby.

Serong steps up
From the moment Caleb Serong palmed off Jack Redden's tackling attempt in the first quarter, it was clear he was going to lead the way for Fremantle and step up in the absence of Andrew Brayshaw. The young star, who was physical and in his opponents' faces, was critical in the fast start with 11 possessions and a goal, and he hardly let up. It was a performance that highlighted his leadership ability as well as his brilliant skill, with his final-quarter goal cementing him as a Glendinning-Allen medallist.

Missed tackles cost Eagles  
Tackling efficiency has been an issue for the Eagles all season and the difference in defensive intent from each side was obvious early. Where the Dockers made their tackles stick and often got an extra number to those contests, the Eagles were palmed off far too often in the first quarter. They won the tackle count 73-64 at the final siren, and there was a noticeable shift after the first break. But they clearly came unprepared for the pressure Fremantle applied and weren't able to lift to that level when chasing their opponents.

FREMANTLE        8.3   10.2   11.2   12.7 (79)
WEST COAST        3.2   4.7   7.9   9.10 (64)    

GOALS
Fremantle: Taberner 3, Schultz 2, Serong 2, Mundy, Cerra, Darcy, Colyer, Treacy
West Coast: Ryan 3, Kennedy 3, Darling 2, Witherden 

BEST
Fremantle: Serong, Ryan, Mundy, Darcy, Taberner, Cerra 
West Coast: Naitanui, Redden, Gaff, Ryan, Witherden, Shuey 

INJURIES
Fremantle: Blakely (hamstring)
West Coast: Kelly (leg) 

SUBSTITUTES
Fremantle: Brett Bewley (replaced Blakely)
West Coast: Zac Langdon (replaced Kelly)

Crowd: 51,692 at Optus Stadium